last updated on 09/12/08
The Leukemia & Lymphoma Society

Leukemia is a malignant disease (cancer) of the bone marrow and blood. It is characterized by the uncontrolled accumulation of blood cells. Leukemia is divided into four categories: myelogenous or lymphocytic, each of which can be acute or chronic. The terms myelogenous or lymphocytic denote the cell type involved. The are four major types of leukemia.

This page provides an overview of the different types of leukemia. For detailed information about each of the types, click on the disease names listed below.

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What is leukemia?
Leukemia is the general term used to describe four different disease-types called:

Acute Myelogenous Leukemia (AML)
Acute Lymphocytic Leukemia (ALL)
Chronic Myelogenous Leukemia (CML)
Chronic Lymphocytic Leukemia (CLL)

The terms lymphocytic or lymphoblastic indicate that the cancerous change takes place in a type of marrow cell that forms lymphocytes. The terms myelogenous or myeloid indicate that the cell change takes place in a type of marrow cell that normally goes on to form red cells, some types of white cells, and platelets.

Acute lymphocytic leukemia and acute myelogenous leukemia are each composed of blast cells, known as lymphoblasts or myeloblasts. Acute leukemias progress rapidly without treatment.

Chronic leukemias have few or no blast cells. Chronic lymphocytic leukemia and chronic myelogenous leukemia usually progress slowly compared to acute leukemias.

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How does leukemia develop?
The four types of leukemia each begin in a cell in the bone marrow. The cell undergoes a leukemic change and it multiplies into many cells. The leukemia cells grow and survive better than normal cells and, over time, they crowd out normal cells.

Normal stem cells in the marrow form three main cell-types: Red cells, platelets and white cells. There are two major types of white cells: germ-ingesting cells (neutrophils and monocytes) and lymphocytes, which are part of the body's immune system and help to fight to infection.

The rate at which leukemia progresses and how the cells replace the normal blood and marrow cells are different with each type of leukemia.

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Acute Leukemia
In acute myelogenous leukemia (AML) and acute lymphocytic leukemia (ALL), the original acute leukemia cell goes on to form about a trillion more leukemia cells. These cells are described as "nonfunctional" because they do not work like normal cells. They also crowd out the normal cells in the marrow; in turn, this causes a decrease in the number of new normal cells made in the marrow. This further results in low red cell counts (anemia). The lack of normal white cells impairs the body's ability to fight infections. A shortage of platelets results in bruising and easy bleeding.

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Chronic Leukemia
In chronic myelogenous leukemia (CML), the leukemia cell that starts the disease makes blood cells (red cells, white cells and platelets) that function almost like normal cells. The number of red cells is usually less than normal, resulting in anemia. But many white cells and sometimes many platelets are still made. Even though the white cells are nearly normal in how they work, their counts are high and continue to rise. This can cause serious problems if the patient does not get treatment. If untreated, the white cell count can rise so high that blood flow slows down and anemia becomes severe.

In chronic lymphocytic leukemia (CLL), the leukemia cell that starts the disease makes too many lymphocytes that do not function. These cells replace normal cells in the marrow and lymph nodes. They interfere with the work of normal lymphocytes, which weakens the patient's immune response. The high number of leukemia cells in the marrow may crowd out normal blood-forming cells and lead to a low red cell count (anemia). A very high number of leukemia cells building up in the marrow also can lead to low neutrophil and platelet counts.

Unlike the other three types of leukemia, some patients with CLL may have disease that does not progress for a long time. Some people with CLL have such slight changes that they remain in good health and do not need treatment for long periods of time. Most patients require treatment at the time of diagnosis or soon after.

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Risk Factors
People can get leukemia at any age. In 2008, about and 44,270 adults and 4,220 children are expected to develop leukemia. It is most common in people over age 60. The most common types in adults are AML and CLL. ALL is the most common form of leukemia in children.

For most types of leukemia, the risk factors and possible causes are not known. Most people who have any of the specific risk factors that have been identified do not get leukemia - and most people with leukemia do not have these risk factors.

Some risk factors for AML are:

Certain chemotherapies used for lymphoma or other types of cancer
Down syndrome and some other genetic diseases
Chronic exposure to benzene (such as in the workplace) that exceeds federally approved safety limits
Radiation therapy used to treat other types of cancer
Tobacco smoke.
Exposure to high doses of radiation therapy is also a risk factor for ALL and CML. Other possible risk factors for the four types of leukemia are continually under study.

Leukemia is not contagious (catching).

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Signs and Symptoms
Some signs or symptoms of leukemia are similar to other more common and less severe illnesses. Specific blood tests and bone marrow tests are needed to make a diagnosis. Signs and symptoms vary based on the type of leukemia.

For acute leukemia, they include:

Tiredness or no energy
Shortness of breath during physical activity
Pale skin
Mild fever or night sweats
Slow healing of cuts and excess bleeding
Black-and-blue marks (bruises) for no clear reason
Pinhead-size red spots under the skin
Aches in bones or joints (for example, knees, hips or shoulders)
Low white cell counts, especially monocytes or neutrophils.
People with CLL or CML may not have any symptoms. Some patients learn they have CLL or CML after a blood test as part of a regular checkup. Sometimes, a person with CLL may notice enlarged lymph nodes in the neck, armpit or groin and go to the doctor. The person may feel tired or short of breath (from anemia) or have frequent infections, if the CLL is more severe. In these cases, a blood test may show an increase in the lymphocyte count.

CML signs and symptoms tend to develop slowly. People with CML may feel tired and short of breath while doing everyday activities; they may also have an enlarged spleen (leading to a "dragging" feeling on the upper left side of the belly), night sweats and weight loss.

Each type of leukemia may have other symptoms or signs that prompt a person to get a medical checkup.

The best advice for any person troubled by symptoms such as a lasting, low-grade fever, unexplained weight loss, tiredness or shortness of breath is to see a healthcare provider.

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A complete blood count (CBC) is used to diagnose leukemia. This blood test may show high or low levels of white cells and show leukemic cells in the blood. Sometimes, platelet counts and red cell counts are low. Bone marrow tests (aspiration and biopsy) are often done to confirm the diagnosis and to look for chromosome abnormalities. These tests identify the leukemia cell-type.

A complete blood exam and a number of other tests are used to diagnose the type of leukemia. These tests can be repeated after treatment begins to measure how well the treatment is working.

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The ways in which patients are affected and how patients are treated are different for each type of leukemia.

Each main type of leukemia has different subtypes. A patient's age, general health and subtype may play a role in determining the best treatment plan. Blood tests and bone marrow tests are used to identify AML, ALL, CML or CLL subtypes.

It is important to get medical care at a center where doctors are experienced in treating patients with leukemia. The aim of leukemia treatment is to bring about a complete remission. Today, more and more leukemia patients are in complete remission at least five years after treatment.

Patients with an acute leukemia need to start treatment right away. Usually, they begin induction therapy with chemotherapy in the hospital.

More inpatient treatment is usually needed even after a patient is in remission. This is called consolidation therapy or post induction therapy. This part of treatment may include chemotherapy with or without allogeneic stem cell transplantation (sometimes called "bone marrow transplantation").

Patients with CML need to begin treatment once they are diagnosed. They usually begin treatment with imatinib mesylate (Gleevec®). Gleevec does not cure CML. But it keeps CML under control for many patients for as long as they take it. For other patients, there are two newer drugs called dasatinib (Sprycel®) and nilotinb (Tasigna®). These drugs also block the BCR-ABL cancer gene, but each works in a different way than Gleevec. Sprycel and Tasigna and are approved for certain CML patients who are resistant or intolerant to prior therapy including Gleevec. All three drugs are taken by mouth.

Allogeneic stem cell transplantation is the only treatment that can cure CML at this time. This treatment is most successful in younger patients. But patients up to 60 years of age who have a matched donor may be considered for this treatment. Allogeneic transplantation can be a high-risk procedure. Studies are under way to see whether CML patients have better long term outcomes with drug therapy or with transplantation.

Some CLL patients do not need treatment for long periods of time after diagnosis. Patients who need treatment may receive chemotherapy or monoclonal antibody therapy alone or in combination. Allogeneic stem cell transplantation is a treatment option for certain patients.

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New Treatment Methods
New cancer treatments are under study in clinical trials to help a growing number of patients achieve remission or be cured of their disease.

AML, ALL, CML and CLL patients who are in remission need to see their doctors regularly for exams and blood tests. Bone marrow tests may be needed from time to time. The doctor may recommend longer periods of time between follow-up visits if a patient continues to be disease free.

Patients and caregivers should talk with their healthcare providers about long-term and late effects of cancer treatment. Cancer-related fatigue is one common long-term effect.

The Society's free fact sheets, Long-Term and Late Effects of Treatment for Childhood Leukemia or Lymphoma and Long-Term and Late Effects of Treatment in Adults have more information on this topic. The Society's free booklet, Learning & Living With Cancer, has more information for caregivers of children with cancer.

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Get Support
After diagnosis, many people with leukemia do survive and live many good, quality years. Knowing more about the disease and its treatment may make it easier to cope.

It may be helpful to write down questions to ask your doctor. Then you can write down your doctor's answers and review them later. You may want to bring a family member or friend with you to the doctor. This person can listen, take notes and offer support. Some patients record information and listen to it at home.

Questions to Ask Your Doctor
Find Support

Please also see the free LLS disease and treatment-specific Guides for more information about ALL, AML, CLL and CML.

LLS offers ongoing education programs on specific types of leukemia. These programs enable you to stay current on the latest information about each type of leukemia and treatment options. The education programs are featured on the Leukemia Education Series and Leukemia News Briefs pages.

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